Recently, furniture and construction materials processed with formalin (usually used to refer to a 37 wt % formaldehyde solution), adhesives containing formaldehyde as a hardening agent, goods made of formaldehyde resins, leather goods tanned with formalin, clothes treated with formalin as a sterilizer or a bleaching agent, and the like are frequently utilized in daily life. Therefore, there are many opportunities for conventional photographic light-sensitive materials to be brought into contact with formaldehyde vapor released from these daily necessities.
In general, a silver halide color photographic material is composed of a support having coated thereon some silver halide emulsion layers each of which has sensitivity in a different region of the spectrum and which contains a coupler capable of reacting with an oxidation product of a color developing agent to form a dye. For example, the photographic material may contain silver halide emulsion layers on a support each of which is sensitive to blue light, green light, and red light and contains a yellow coupler, a magenta coupler, and a cyan coupler, respectively, in a conventional case. After exposure to light, the photographic material is subjected to color development processing to form yellow, magenta, and cyan color dye images in these silver halide emulsion layers, respectively. In such a multilayer color photographic material, it is desired that each silver halide emulsion layer be well balanced with respect to sensitivity and gradation, in order to obtain an excellent color image. It is also desired that the photographic properties of the photographic material are not changed during storage for a long period of time either before or after exposure to light until it is subjected to color development processing.
However, when a conventional silver halide color photographic material is brought into contact with formaldehyde vapor before color development processing, not only is the coupler incorporated therein consumed by the reaction with formaldehyde but an undesirable by-product is also formed. As a result, degradation of the photographic properties, for example, decrease in color density, increase in color stain and fog, etc., occurs. The degradation of photographic properties due to formaldehyde vapor is serious in the case of the so-called 4-equivalent couplers having an active methylene group. Particularly, magenta couplers tend to be adversely affected by formaldehyde.
It has hitherto been proposed that a compound which reacts with formaldehyde be incorporated into a silver halide color photographic material containing a coupler for the purpose of preventing the degradation of photographic properties due to formaldehyde vapor. However, known compounds for preventing the degradation of photographic properties due to formaldehyde vapor (hereinafter referred to as formaldehyde scavengers) in conventional silver halide color photographic materials containing an oil-soluble 4-equivalent magenta coupler, as described in Japanese Patent Publication Nos. 38418/73 and 23908/76, U.S. Pat. Nos. 3,652,278, 3,770,431, 4,414,309, 4,411,987, 4,490,460 and 4,435,503, Research Disclosure, Vol. 101, RD No. 10133 (August 1972), etc., only have a slight ability with respect to fixing formaldehyde vapor. Therefore, sufficient effects cannot be obtained. Further, when they are used in a large amount, a disadvantage is encountered, in that the film properties of the photographic light-sensitive material are degraded.
Moreover, the degradation of photographic properties due to formaldehyde vapor is seriously observed with magenta color images, in particular, in case of using conventional 4-equivalent magenta couplers. In order to overcome this problem, another method using 5-pyrazolone 2-equivalent magenta couplers as described in Japanese Patent Application (OPI) Nos. 62454/80, 38043/81, 4044/82, 17440/83, 50537/83, 85432/83, 117546/83, 126530/83, 170/79, 10491/79, 21258/79, 46453/78, 2953/85, 23855/85, and 170854/85 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application"), U.S. Pat. Nos. 3,257,554, 3,432,521, 3,935,015, 4,126,462, 4,189,321, 4,241,168, 4,264,723, 4,301,235, 4,308,343, 4,310,618, 4,310,619, 4,334,011, 4,351,897, 4,367,282, 4,407,936, 4,436,808 and 4,522,915, etc.
When such 2-equivalent magenta couplers are employed in place of conventional 4-equivalent magenta couplers, such is observed to provide improved effects on the decrease in color density occurred when the photographic materials are brought into contact with formaldehyde vapor during storage. In contrast with this, however, the increases in fog is markedly promoted.
Further, it is found that such increases in fog occurs not only with respect to the magenta color, but also occurs with respect to the cyan and yellow couplers. This is a serious defect in the photographic properties. The reason for the increase in fog is not completely clear, but it may occur as follows. That is, 4-equivalent magenta couplers conventionally used react with formaldehyde vapor to decrease the concentration of formaldehyde vapor in the coated layer when they are brought into contact with formaldehyde vapor during storage. As a result, they act to decrease the reducing function of formaldehyde on a silver halide emulsion in compensation for the degradation of their color forming property. On the contrary, in case of using 2-equivalent magenta couplers which do not substantially react with formaldehyde, their color forming property does not decrease, but the reducing function of formaldehyde to the silver halide emulsion increases by means of a rise in the concentration of formaldehyde in the coated layer. However, such a mechanism is still uncertain, and requires further investigations in the future.
On the other hand, 2-equivalent magenta couplers having a pyrazoloazole skeleton as described in Japanese Patent Publication No. 30895/73, Japanese Patent Application (OPI) Nos. 17196/84 and 99437/84, U.S. Pat. Nos. 3,725,067 and 4,500,630, etc., are also known as a different type of 2-equivalent magenta couplers from the 5-pyrazolone type. It is known that these couplers undergo a small change in their color forming property when they are brought into contact with formaldehyde vapor in comparison with the case wherein they do not. However, these pyrazoloazole type couplers have serious problems per se in that degradation of photographic properties, for example, decrease in sensitivity and deterioration of color forming property is severe during storage under conditions free from formaldehyde vapor. In particular, a phenomenon in which a latent image formed in silver halide upon exposure to light is gradually destroyed and disappears during a period of storage prior to development, that is, a so-called latent image fading, occurs to a significant extent with these 2-equivalent magenta couplers having a pyrazoloazole skeleton. Further, a severe problem is that such latent image fading greatly accelerates when these pyrazoloazole type magenta couplers are employed together with formaldehyde scavengers for the purpose of restraining fog due to formaldehyde vapor.
On the other hand, in view of the recent trends, such as water shortages, steep rises in sewarage rates and fuel expenses, increased environmental concerns, and the like, it has been demanded to develop a method of processing using a reduced amount of washing water. As a countermeasure for these problems, methods in which a washing step is omitted or the amount of washing water is extremely decreased have been proposed. For example, U.S. Pat. No. 4,336,324 discloses inclusion of multiple countercurrent stabilization processing; Japanese Patent Application (OPI) No. 134636/83 discloses use of a stabilizer containing a bismuth salt; and Japanese Patent Application (OPI) No. 18631/83 teaches use of an organic phosphonic acid. However, any of these proposed methods involves problems, such as liability to variations in minimum density, or formation of stains after processing.
It has recently been demanded in the market to deliver developed prints to customers as soon as possible, and, therefore, there is increasing necessity for shortening development processing steps. In color photographic materials, especially color negative films, using silver iodobromide type emulsions, a desilvering step occupies a considerable proportion of the total time required for development processing, and it has thus been desired to shorten the desilvering step.